The present invention relates to a vehicle instrument cluster, and more particularly to a light guide assembly for an illuminated display that increases light efficiency.
An instrument cluster for a vehicle is traditionally located on a vehicle dashboard and includes several displays or dials that indicate various vehicle operating conditions. For example, an instrument cluster may include a speedometer, a tachometer, an engine condition indicator, and other known types of gauges. These gauges are illuminated to facilitate reading of the information by the vehicle occupants.
Instrument clusters include a printed circuit board (PCB) with electronic components for controlling operation of the instrument clusters. Light sources, such as light emitting diodes (LEDs), are typically mounted to the PCB. A light housing is used to contain the light produced by the light sources inside the instrument cluster and prevent unwanted light leakage. The instrument cluster further includes a display or dial on which the graphical image is formed or mounted.
The instrument cluster may include a light guide formed as a piece of clear material which channels the light received from the light source and redistributes the light over the display. Disadvantageously, known light guides have not satisfactorily provided uniform distribution of light over the entire display. In addition, an increased number of light sources may be required to provide the desired uniform light distribution.
The use of compensation is known for providing evenly distributed illumination over the entire display of the instrument cluster. Compensation is achieved by darkening the bright spots of the dial to the level of the darkest spot of the dial. This requires the application of a coating to the display or dial to absorb light in certain areas. Disadvantageously, the light efficiency provided by an instrument cluster utilizing compensation may be poor because a large quantity of light produced by the light source is absorbed by the compensation layer.
Accordingly, it is desirable to provide a vehicle instrument cluster that increases the efficiency of light utilized for illuminating a display while providing compensation free display illumination.